
The determination of the coefficient \(\alpha \)  in Equation (REF ) should be better analyzed. See [1]} for a first hint.

The impossibility of ensuring global stability in the context of model-free control should be replaced by a suitable replanning of the reference trajectory (see, e.g., [2]} for a replanning example in the context of flatness-based control).

The extension to iPDs of the hardware for iPs in [3]}.

The extension of the treatment of multi-input multi-output (MIMO) systems in [4]}.

The extension to the discrete-time approach in [5]}.

A more thorough study of iPIDs in order to determine possible benefits with respect to iPDs.Would for instance the most convincing application [6]} to an electromagnetic robot, where an iPID is employed, be improved or not by an iPD?

The regulation via PIDs of systems with delays is far from being fully understood (see, e.g., [7]}, [8]}). It would be rewarding to extend, if possible, the time series setting in [9]} for supply chain management.

The approach to machine learning sketched in [1]} should benefit from the unicity of the feedback loop advocated here. See also [5]}.

